This invention relates generally to a method of treating cardio-cerebrorenovascular disease as well as avoiding potential cardiocerebrorenovascular disease, and the symptoms thereof, wherein a substrate of Nitric Oxide Synthase (xe2x80x9cNOSxe2x80x9d) and an agonist of NOS are combined to produce a beneficial effect.
Much focus in the area of cardiac disease has been on the presence of cholesterol in the body. Hypercholesterolemia is known to be a primary risk factor for death from coronary heart disease. It is known that 50% or more of the total body cholesterol in humans is derived from intrinsic biosynthesis. It is also known that a rate-limiting step of major significance in the biosynthesis of cholesterol is at the level of the enzyme known as 3-hydroxy-3-methylglutaryl-coenzyme A reductase or Hmg-CoA reductase. A general class of compounds is known in the art which inhibit and reduce the intrinsic biosynthesis of cholesterol in order to reduce the risk factor of hypercholesterolemia and coronary artery death. This general class of compounds is known as inhibitors of Hmg-CoA reductase.
An alternative approach to treating cardiac disease is to effect the dilation of vascular conduits in the body. In this regard, nitric oxide has been shown to be formed enzymatically as a normal metabolite from arginine in vascular endothelium and provides an important component to the formation of endothelium-derived relaxing factor (EDRF). EDRF appears to be equivalent to Endothelium Derived Nitric Oxide (EDNO) and as used herein EDRF and EDNO are interchangeable unless otherwise indicated. Macrophages and neurons have also been shown to produce nitric oxide in the body as a component of their cell killing and/or cytosolic function.
Recently it has been established that a family of enzymes called Nitric Oxide Synthase (xe2x80x9cNOSxe2x80x9d) form nitric oxide from L-arginine, and the nitric oxide produced is responsible for the endothelium dependent relaxation and activation of soluble guanylate cyclase, nuerotransmission in the central and peripheral nervous systems, and activated macrophage cytotoxicity.
Nitric Oxide Synthase, occurs in many distinct isoforms which include a constitutive form (cNOS) and an inducible form (iNOS). The constitutive form is present in normal endothelial cells, neurons and some other tissues. Formation of nitric oxide by the constitutive form in endothelial cells is thought to play an important role in normal blood pressure regulation, prevention of endothelial dysfunction such as hyperlipodemia, arteriosclerosis, thrombosis, and restenosis. The inducible form of nitric oxide synthase has been found to be present in activated macrophages and is induced in vascular smooth muscle cells, for example, by various cytokines and/or microbial products.
The conversion of precursor substrates of EDNO such as L-arginine into nitric oxide is enzymatically catalyzed by NOS and the resulting by-product of the conversion of L-arginine is L-citrulline. Although it was initially described in endothelium, NOS activity has now been described in many cell types. Brain, endothelium, and macrophage isoforms appear to be products of a variety of genes that have approximately 50% amino acid identity. NOS in brain and in endothelium have very similar properties, the major differences being that brain NOS is cytosolic and the endothelial enzyme is mainly a membrane-associated protein.
Functionally, the constitutive form of Nitric Oxide Synthase (xe2x80x9ccNOSxe2x80x9d), which is the predominant synthase present in brain and endothelium, may be active under basal conditions and can be further stimulated by increases in intracellular calcium that occur in response to receptor-mediated agonists or calcium ionophores. cNOS appears to be the xe2x80x9cphysiologicalxe2x80x9d form of the enzyme and plays a role in a diverse group of biologic processes. In vitro studies suggest that the activity of nitric oxide synthase can be regulated in a negative feedback manner by nitric oxide itself. In cardiocerebrorenovascular circulation, the primary target for constitutively produced nitric oxide is believed to be soluble guanylate cyclase located in vascular smooth muscle, the myocardium (myocytes) and coronary vascular smooth muscle.
In contrast to the cNOS, the inducible, calcium-independent form, iNOS was initially only described in macrophages. It is now known that induction of nitric oxide synthase can occur in response to appropriate stimuli in many other cell types. This includes both cells that normally do not express a constitutive form of nitric oxide synthase, such as vascular smooth muscle cells, as well as cells such as those of the myocardium that express considerable levels of the constitutive isoform.
iNOS exhibits negligible activity under basal conditions, but in response to factors such as lipopolysaccharide and certain cytokines, expression occurs over a period of hours. The induced form of the enzyme produces much greater amounts of NO than the constitutive form, and induced NOS appears to be the xe2x80x9cpathophysiologicalxe2x80x9d form of the enzyme because high concentrations of NO produced by iNOS can be toxic to cells. Induction of iNOS can be inhibited-by glucocorticoids and some cytokines. Relatively little is known about postranscriptional regulation of iNOS. Cytotoxic effects of NO are probably largely independent of guanylate cyclase and cyclic GMP formation. Most of the research in the area has focused on inhibitors of iNOS stimulation using various derivatives of L-arginine.
Research into the area of cNOS activation reveals a number of agonist of cNOS some of which have been described in U.S. Pat. No. 5,543,430, which is hereby incorporated by reference in its entirety. However, until now there was no known research indicating Hmg-CoA reductase inhibitors were capable of functioning as agonist of cNOS.
The term xe2x80x9csubjectxe2x80x9d as used herein to mean any mammal, including humans, where nitric oxide formation from arginine occurs. The methods herein for use on subjects contemplate prophylactic use as well as curative use in therapy of an existing condition.
The term xe2x80x9cnative NOxe2x80x9d as used herein refers to nitric oxide that is produced through the bio-transformation of L-arginine or the L-arginine dependent pathway. xe2x80x9cEDRFxe2x80x9d or xe2x80x9cEDNOxe2x80x9d may be used interchangeably with xe2x80x9cnative NOxe2x80x9d. The term endpoints as used herein refers to clinical events encountered in the course of treating cardiovascular disease, up to and including death (mortality).
L-arginine as used herein includes all biochemical equivalents (i.e. salts, precursors, and its basic form). L-arginine as defined herein appears to function as a substrate of cNOS.
xe2x80x9cTo mixxe2x80x9d, xe2x80x9cmixingxe2x80x9d, or xe2x80x9cmixture(s)xe2x80x9d as used herein means mixing a substrate (i.e. L-arginine) and an agonist (i.e. Hmg-CoA reductase inhibitor): 1) prior to administration (xe2x80x9cin vitro mixingxe2x80x9d); 2) mixing by simultaneous and/or consecutive, but separate (i.e. separate intravenous lines) administration of substrate (L-arginine and agonist to cause xe2x80x9cin vivo mixingxe2x80x9d; and 3) the administration of a NOS agonist after saturation with a NOS substrate (i.e. L-arginine is administered to build up a supply in the body prior to administering the NOS agonist (nitroglycerin or Hmg-CoA reductase)); or any combination of the above which results in the combination of therapeutic amounts of a NOS agonist and a (NOS substrate in an additive or synergistic way with regard to the treatment of vascular disease.
Agonist refers to an agent which stimulates the bio-transformation of a substrate such as L-arginine to EDNO or EDRF either through enzymatic activation or increasing gene expression (i.e. increased protein levels of c-NOS). Of course, either or both of these mechanisms may be acting simultaneously.
It is an object of this invention to provide a method of preventing, treating, arresting, or ameliorating disease conditions which are benefited by the bio-transformation of a substrate into endogenous nitric oxide or xe2x80x9cnativexe2x80x9d nitric oxide.
It is another object of this invention to provide a method of preventing, treating, arresting, or ameliorating disease conditions which are benefited by the bio-transformation of L-arginine into xe2x80x9cnativexe2x80x9d nitric oxide through enzyme activation of NOS.
It is another object of this invention to ameliorate or avoid tachycardia and prevent or treat ischemia.
It is another object of this invention to achieve a beneficial effect when treating disease conditions by increasing or maximizing the production of xe2x80x9cnativexe2x80x9d nitric oxide, and reducing clinical endpoints to include mortality.
It is another object of this invention to prevent reperfusion injury in subjects who have had abrupt restoration of blood flow.
It is a further object of this invention to provide a mixture of inhibitors of Hmg-CoA reductase and biological equivalents of L-arginine for the treatment of hypertension, hypertensive heart disease, coronary heart disease, including arteriosclerosis, angina, myocardial infarction, coronary thrombosis, restenosis post angioplasty, and sudden death, as well as a wide range of cardiovascular disease (heart failure, stroke, and peripheral vascular diseases), and renovascular ischemia/hypertension.
These and other objects of this invention are provided by one or more of the embodiments provided below.
In one embodiment of the invention, therapeutically effective amounts of a precursor of EDNO and an agonist of NOS are combined prior to administration to a patient. In another embodiment of the invention, therapeutically effective amounts of a precursor of EDNO and an agonist of NOS are combined prior to administered separately and mixed xe2x80x9cin vivoxe2x80x9d.
In another embodiment of the invention, therapeutically effective amounts of L-arginine and inhibitors of Hmg-CoA reductase are mixed at a physiologically acceptable pH and administered to a patient.
In another embodiment of the invention a method for treating hypertension in a subject by vasodilation or vasorelaxation comprises: selecting a hypertensive subject; administering L-arginine and Hmg-CoA reductase inhibitors to the subject; obtaining periodic blood pressure measurements of the subject; and continuing administration of L-arginine and Hmg-CoA reductase inhibitors until a desirable blood pressure or therapeutic effect is detected in the subject. A desirable blood pressure in a hypertensive subject should ultimately be within the following ranges: systolic preferably in the range of 95-180 mmHg, more preferably in the range of 105-165 mmHg, and even more preferably in the range of 120 to 140 mmHg; and diastolic preferably in the range of 55-115 mmHg, more preferably in the range of 65-100 mmHg, and even more preferably in the range of 70 to 90 mmHg, and most preferably 75-85 mmHg. Under no circumstances should the systolic be permitted to go below 95 mmHg.
Another embodiment of the present invention is a method for preventing or treating cardiovascular disease in a non-hypertensive subject by vasodilation or vasorelaxation comprising: selecting a subject; administering to said subject a formulation comprising a mixture of an inhibitor of Hmg-CoA reductase and an endothelium dependent source of nitric oxide (i.e., L-arginine); obtaining periodic measurements of vasorelaxation on the subject and; continuing administration of the formulation until a desirable state of vasorelaxation or desirable therapeutic effect is detected on the subject. A desirable state-of vasorelaxation is for example a lowering of the systolic by about 20 mmHg and a lowering of the diastolic by about 10 mmHg. Under no circumstances should the systolic be lowered less than 95 mmHg.
Yet another embodiment is a method for stimulating cNOS in a subject which comprises: selecting a subject; administering to said subject a formulation comprising a mixture of L-arginine and inhibitors of Hmg-CoA reductase, so as to maximize xe2x80x9cnativexe2x80x9d NO production and reduce endpoints to include mortality.